There are a broad spectrum of technical and medical endeavors that require application of exact quantities of liquids For example, the dyeing of slides for microscope work, the applying of catalyst to cure epoxies and the administering of drugs, all require that precise amounts of a critical liquid(s) be metered to a predetermined use site. Present technology devices for accomplishing these tasks include syringes, brushes, pipets and "eye droppers". To provide accuracy of application within a requisite quantity range, it is often necessary to substantially dilute the use liquid in a carrier and supply more volume of the carrier/use liquid combination.
A more sophisticated approach for controlled dispensing of liquids is described in U.S. Pat. No. 4,475,666, which uses a microcomputer controlled motor to operate the piston of a syringe. This system has a detection and feedback loop that monitors and controls the piston drive motor to assure accurate ejection of the quantities selected (i.e. entered into the system microcomputer) by the user. This system is relatively complicated structurally and requires servo systems that compensate for mechanical backlash and motor drive variations.